NEW YORK -- Lindsay Lohan made David Letterman's heart beat faster when she told him she plays a stripper in her next film, "I Know Who Killed Me."

"You're just gonna kill me, you know I have a heart condition. You're just gonna kill me," the CBS' "Late Show" host said Wednesday night.

The 20-year-old actress said the audience will be seeing "a lot" of her in the "really dark, scary film."

Lohan also said she took lessons for the role.

"It's really difficult to get yourself up there," she said.

Lohan was at a loss for words when Letterman talked about her "Georgia Rule" co-star Jane Fonda. Last year, Fonda praised a studio executive's scolding of Lohan for her absences on the set of the movie.

"You're 20, Jane Fonda is 70 for god's sakes and looks just tremendous, and more than looks great, has this palpable sense of vitality," Letterman said. "It radiates."

Lohan was silent for a moment, then replied: "She does, no, she's amazing."

"Georgia Rule," also starring Felicity Huffman, was to open in theaters Friday.